CN112376544B - A freezing device and method for freezing strata in stages - Google Patents

Abstract

The invention relates to a freezing device for freezing stratums in sections, which at least comprises a protection tube, a radiating tube and a solid-state refrigerating device, wherein the solid-state refrigerating device is composed of a plurality of semiconductor refrigerating sheets which are directionally arranged, and the semiconductor refrigerating sheets can be axially and/or circumferentially distributed between the protection tube and the radiating tube; under the condition that the control unit can independently control the circuit, the current magnitude and the direction of any group of semiconductor refrigeration pieces, the control unit can realize segmented freezing according to the mode of independently controlling the semiconductor refrigeration pieces with certain length in the protection pipe. The freezer can freeze the stratum directly after being electrified and refrigerated without building a freezing station, thereby greatly reducing the engineering cost and the construction period, reducing the cost and improving the working efficiency; segmented freezing, directional freezing and forced unfreezing can be realized according to engineering requirements, so that the refrigeration cost is saved and the construction period is shortened; natural water is adopted for cooling in a circulating way, so that the risk of environmental pollution caused by leakage does not exist.

Description

A freezing device and method for freezing strata in stages

The application number of the present invention is 201910426509.5, the application date is May 22, 2019, the application type is invention, and the application name is a divisional application of a thermoelectric refrigeration artificial formation freezer.

technical field

The invention belongs to the field of underground engineering design, and in particular relates to a freezing device and method for freezing stratum in sections.

Background technique

The artificial stratum freezing method is to use artificial refrigeration to send low-temperature refrigerant into the water-bearing stratum around the excavation body, so that the water in the stratum is continuously frozen into ice in the temperature field below its freezing point, and the water in the stratum is frozen. Soil particles are cemented with ice to form an impermeable overall structure, and the overall strength and elastic modulus of this frozen soil structure are much larger than those of non-frozen soil, which will freeze the stratum around the excavation into a closed continuum (frozen soil). earth wall) to resist ground pressure and isolate the connection between groundwater and the excavated body, then excavation and construction support can be carried out under the protection of a closed continuous frozen earth wall. This method is suitable for loose and unstable alluvial formations, fractured aquifers, soft mudstones, and rock formations with extremely high water content and hydraulic pressure. The specific process of the freezing method is to bury the freezer in the formation to be treated, and the negative temperature cold medium circulating in the freezer absorbs the heat of the formation and freezes the water in the formation around the freezer from near to far into ice. The rock and soil particles are cemented together by ice. If the frozen pipes are buried at appropriate intervals, the adjacent frozen soil columns will continue to expand and connect to form a continuous frozen soil wall or a closed frozen soil structure. In this way, the frozen soil wall has complete water resistance and high strength, and can As a protective measure for temporary excavation. The traditional freezer is mainly composed of two parts: the outer freezing pipe and the inner liquid supply pipe. The brine enters the liquid supply pipe from the liquid distribution ring, reaches the bottom and flows into the annular space formed by the liquid supply pipe and the freezing pipe, and then returns to the liquid. The tube enters the collecting ring, and this cycle sequence is called positive cycle, and vice versa is reverse cycle.

Traditional freezers have the following disadvantages:

1. The construction process is complicated and the time is too long. First, it is necessary to establish a freezing station, mainly an ammonia compression refrigeration unit, and then drill holes in the part to be frozen, lower the freezer, turn on the ammonia compression refrigeration unit, reduce the temperature of the brine, and then rely on the circulation of the brine in the freezer to continuously remove water from the formation. Absorb heat to achieve the purpose of freezing. The construction preparation period and the freezing period take a long time.

2. Excessive power is required. The freezing project based on the negative temperature brine cycle needs to first convert electrical energy into mechanical energy, and mechanical energy into thermal energy. The conversion process is complicated, and a lot of electrical energy is wasted in the middle.

3. Leaks can easily cause pollution. During the freezing process, the frozen pipe is pre-cooled and shrunk, forming shrinkage stress inside and freezing outside, resulting in extrusion force, so the frozen pipe is easy to break, resulting in leakage of salt water, which not only affects the progress of the project, but also causes pollution to the formation.

4. The construction cost is high. Since the freezing station unit needs special maintenance, and the construction time is long, it consumes a lot of electric energy.

Therefore, the existing freezing system engineering construction cost is too high.

In addition, the single length of the brine freezer used in the existing urban underground engineering usually ranges from several meters to more than ten meters, and in the freezing project of the mine, the freezing depth often reaches hundreds of meters or even thousands of meters. In such a long freezing range, the conventional brine freezer needs to circulate and cool a large amount of brine in the whole basin during the brine cooling period. The longer the freezing tube length, the larger the brine volume, and the longer the cooling time, which will seriously delay the construction period. On the other hand, the artificial excavation and support under the sealing water and support of the frozen soil wall are carried out in stages. The active freezing stage of the brine freezer freezes the soil excavated in different periods indiscriminately and synchronously, resulting in long-term The heat of the excavated soil enters the circulating brine, which increases the workload of the compression refrigeration unit. Therefore, the segmental freezing function of the freezer plays an important role in saving energy in the artificial formation freezing project. Therefore, there is a need for a freezer that can flexibly and reasonably adjust the working states of different sections according to the tunneling speed of underground projects, so as to reduce energy waste as much as possible and achieve good economy under the premise of meeting safety requirements and construction period requirements.

SUMMARY OF THE INVENTION

Aiming at the problems existing in the prior art, the present invention provides a thermoelectric refrigeration artificial formation freezer with simple structure, short construction period, low cost, and no leakage; it can also realize segmental freezing, directional freezing and forced thawing according to engineering needs.

In order to achieve the above purpose, the technical scheme adopted in the present invention is: provide

A thermoelectric refrigeration artificial formation freezer, comprising a protection device arranged outside, a heat sink arranged inside, and a solid-state refrigeration device arranged between the protection device and the heat sink, the solid-state refrigeration device is a semiconductor refrigeration sheet, the semiconductor The cooling sheet has end heat-absorbing and exothermic ends, the heat-absorbing end is attached to the protection device, and the exothermic end is attached to the heat-dissipating device. After power-on, the heat-absorbing end absorbs the formation heat, and the exothermic end takes the formation heat away through the heat-dissipating device; semiconductor The cooling chip controls its circuit, current magnitude and direction through the control unit.

Further, according to the above-mentioned thermoelectric refrigeration artificial formation freezer, the semiconductor refrigeration sheet has a sheet-like structure or an arc-shaped structure; and the refrigeration level is single-stage refrigeration, two-stage refrigeration or multi-stage refrigeration.

Further, according to the above-mentioned thermoelectric refrigeration artificial formation freezer, a plurality of semiconductor refrigeration sheets are evenly distributed between the protection device and the heat dissipation device along the axial or circumferential direction, and each semiconductor refrigeration sheet is controlled by a control unit.

Further, in the above-mentioned thermoelectric refrigeration artificial formation freezer, the control unit includes a single-chip microcomputer and an H-bridge, the single-chip microcomputer communicates with a computer through an interface, receives commands from the computer and controls the work of the H-bridge; the H-bridge receives the single-chip microcomputer command, Regulates the current of the semiconductor cooler.

Further, in the above-mentioned thermoelectric refrigeration artificial formation freezer, the heat dissipation device is a water-cooled sleeve-type radiator, including an external heat dissipation pipe and an internal liquid supply pipe, and a liquid return space is formed between the heat dissipation pipe and the liquid supply pipe. .

Further, according to the above-mentioned thermoelectric refrigeration artificial formation freezer, the radiating pipe is provided with a liquid drain hole, and the liquid drain hole is communicated with the liquid return space.

Further, in the above-mentioned thermoelectric refrigeration artificial formation freezer, the protection device is a protection tube with good thermal conductivity and high strength, the protection tube is a closed thin tube, and the cross section of the closed thin tube is circular or polygonal structures.

Further, according to the above-mentioned thermoelectric refrigeration artificial formation freezer, the external structure of the heat dissipation pipe is adapted to the internal structure of the protection pipe.

Further, in the above-mentioned thermoelectric refrigeration artificial formation freezer, the space formed between the protection device, the cooling device and the solid-state refrigeration device is provided with a temperature sensor for detecting the temperature of the protection device and the cooling device. Installed in the wire and temperature sensor slot and connected with the computer.

The beneficial technical effect of the present invention is:

(1) The freezer of the present invention can directly freeze the stratum by setting a solid-state refrigeration device between the protection device and the heat-dissipating device, and the stratum can be directly frozen when the power is turned on. Reduce engineering costs and duration.

(2) The solid-state refrigeration device of the present invention can realize segmental freezing and directional freezing by controlling the circuit switch of the control unit, thereby saving electric energy; by changing the current or voltage in the circuit, the freezing intensity can be changed, and the digging time can be shortened; by changing the circuit In the direction of the current in the middle, it can be forced to thaw immediately after the excavation project is completed, which can shorten the thawing time of the artificially frozen stratum, and more reasonably arrange the grouting construction in the later stage, so as to better control the settlement. Great significance, and can greatly save refrigeration and maintenance costs.

(3) The heat dissipation device adopts natural water circulation to dissipate heat, and there is no risk of polluting the environment after leakage.

Description of drawings

1 is a cross-sectional view of a freezer of the present invention;

Fig. 2 is the front view of the freezer of the present invention;

Fig. 3 is the structural representation of freezer segment freezing of the present invention;

Fig. 4 is the structural representation of freezer directional freezing of the present invention;

Fig. 5 is the arrangement diagram of the semiconductor refrigeration chip of the present invention;

Fig. 6 is the freezer control principle diagram of the present invention;

FIG. 7 is a circuit diagram of the control unit of the present invention.

List of reference signs

1: Protection tube 2: Semiconductor cooling sheet 3: Radiator tube

4: Exothermic end 5: Heat absorbing end 6: Liquid supply pipe

7: Wire and temperature sensor slot 8: Control unit 9: Drain hole

10: Pipe head 11: Strong frozen soil area 12: Weak frozen soil area

13: Area to be excavated 14: Temperature sensor 15: Freezer

Detailed ways

The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

As shown in Figures 1-3, it is a thermoelectric refrigeration artificial formation freezer provided by the present invention, which can be used not only for freezing artificial formations, but also for freezing other frozen bodies. It includes a protection device, a solid-state refrigeration device, a heat-dissipating device and a control unit 8. The heat-dissipating device is arranged in the protection device, and the solid-state refrigeration device is arranged between the protection device and the heat-dissipating device, and closely fits the protection device and the heat-dissipating device. The control unit 8 Circuits, current magnitude and direction used to control solid state refrigeration units. A temperature sensor 14 for detecting the temperature of the protection device and the heat sink is arranged in the space formed between the protection device, the heat sink and the solid-state refrigeration device. The temperature sensor 14 is installed in the wire and the temperature sensor slot 7 and connected to the computer.

The protection device is a protection tube 1 with good thermal conductivity and high strength. The protection tube 1 is an airtight thin tube made of metal, which can transmit heat efficiently and protect internal components from damage. It includes a pipe body and a pipe head 10, and the cross-section of the pipe body is a circular structure or a polygonal structure such as a triangle, a quadrilateral, a pentagon, a hexagon, etc., which is determined according to actual use needs, and the present invention is exemplified by a hexagonal structure. ; The pipe head 10 is a conical structure, which is convenient for drilling into the formation.

The heat dissipation device is a water-cooled sleeve-type radiator, including a heat dissipation pipe 3 arranged on the outside and a liquid supply pipe 6 arranged inside. A liquid return space is formed between the heat dissipation pipe 3 and the liquid supply pipe 6, and a drain pipe is provided on the heat dissipation pipe 3. Liquid hole 9, the liquid drain hole 9 communicates with the liquid return space. During operation, the circulating cooling water flows in from the liquid supply pipe 6, flows into the liquid return space in the reverse direction at the end of the liquid supply pipe 6, and is discharged through the liquid discharge hole 9, thus completing the heat dissipation work, as shown in Figure 2, the direction of the arrow in the figure is: The cooling water circulation flow direction, it should be noted that the water flow can be reversed. In order to better arrange the solid-state refrigeration device, the external shape of the heat dissipation pipe 3 is adapted to the internal shape of the protection pipe 1 .

The solid-state refrigeration device is a semiconductor refrigeration sheet 2, which is also called a thermoelectric refrigeration sheet. The thermoelectric refrigeration sheet uses the Peltier effect of semiconductor materials. When the direct current passes through the galvanic couple formed by two different semiconductor materials in series , the two ends of the galvanic couple can absorb heat and release heat respectively, so as to realize the cooling effect immediately. When the semiconductor refrigeration chip 2 is working, the temperature difference between the cold and hot ends is fixed, so reducing the temperature of the cold end can obtain a lower temperature of the hot end, thereby improving the cooling capacity of the cold end.

The semiconductor refrigeration sheet 2 has a sheet-like structure, an arc-shaped structure or other structural shapes, which are determined according to actual use requirements. The semiconductor refrigeration sheet 2 can choose single-stage refrigeration, two-stage refrigeration or multi-stage refrigeration, and the refrigeration level is selected according to the required freezing intensity to meet the refrigeration requirements.

The semiconductor refrigerating sheet 2 includes a heat absorbing end 5 and a heat releasing end 4. The heat absorbing end 5 is closely attached to the inner wall of the protection tube, and the heat releasing end 4 is closely attached to the outer wall of the heat dissipation tube 3. In this way, after the power is turned on, the heat absorbing end 5 can be more suitable. The heat of the external rock and soil mass is quickly absorbed, the temperature of the soil mass is lowered, and the exothermic end 4 can transfer the heat out more quickly.

The arrangement position, quantity and angle of the semiconductor refrigeration chips 2 can be changed as required, and various arrangement modes can be selected while satisfying the structure of the protection pipe and the heat dissipation pipe.

In the freezer of the present invention, a plurality of semiconductor refrigeration fins 2 can be evenly distributed along the axial or circumferential direction between the protection pipe 1 and the heat dissipation pipe 3, and each semiconductor refrigeration fin 2 is controlled by the control unit 8, so as to realize segmental freezing , Directional Freeze, Adjust Freeze Strength and Force Thaw.

Sectional freezing: As shown in Figure 3, that is, during the excavation process, for Section A, which is excavated first, it can be energized and frozen first, while for Section B, it can be energized and frozen after a period of delay according to the progress of the project. In this way, it can not only meet the needs of the project, but also greatly save energy. Of course, according to the actual freezing length (or depth) needs of the project, it can be divided into multiple sections, and only the simplest 2-stage subsection freezing implementation method is demonstrated here.

Directional freezing: As shown in Figures 4 and 5, taking the single-loop freezing as an example, by controlling the circuit of the semiconductor cooling chip 2, the freezer 15 is made to face the three semiconductor cooling chips 2 in the permafrost area 11 to absorb heat, and the outer side faces the formation. Freeze; at the same time, by controlling the circuit of the semiconductor refrigeration sheet 2, the freezer 15 is closed to the three circuits of the semiconductor refrigeration sheet 2 facing the weakly moving soil area, so as to weaken the freezing quantity of the frozen soil entering the area to be excavated 13. As a result, a low-temperature and high-strength outer ring freezing wall can be formed on the outside of the freezer 15, and the directional freezing effect of the thickness of the inner freezing wall can be reduced, which can reduce the difficulty of excavating the soil in the area to be excavated 13, and reduce the time required for excavation operations. cost and time.

Adjust the freezing intensity: In the active freezing period, the maximum working current is used to obtain the best cooling effect. When the soil reaches the freezing temperature requirement, it enters the maintenance freezer, which can reduce the current, so that the freezing effect of the freezer can just meet the requirements. The condition that the frozen soil does not thaw can greatly save electricity consumption.

Forced thawing: After the supporting structure is completed, the embedded freezer can realize the exchange of the heat-absorbing end of the semiconductor refrigeration sheet and the exothermic end of the semiconductor refrigeration sheet through the reverse current, and force the thawing of the artificially frozen stratum. This can greatly shorten the melting time of the artificially frozen strata, and arrange the grouting construction in the later stage more reasonably, so as to better control the settlement, which is of great significance for controlling engineering risks and shortening the construction period.

As shown in Figure 6, it is the control principle diagram of the freezer. The bold line in the figure is the signal line, and the thin line is the power line. The freezer provides the required working voltage of each part through the direct current power supply DC, and the control unit 8 is regulated by the computer. During operation, the temperature of the outer wall of the protection pipe and the temperature field information in the frozen soil collected by the temperature sensor 14 are returned to the computer, and the computer is assisted to regulate and control the control unit 8 through program operation. The control unit 8 changes the power of the semiconductor refrigeration chip by controlling the duty ratio of the output PWM signal, thereby adjusting the refrigeration intensity. For example, in the active freezing period, full power cooling is used to obtain the best cooling effect; when the soil reaches the freezing temperature requirement, it enters the maintenance freezing period, and the control unit 8 adjusts the duty cycle of the PWM signal sent by it to reduce the The cooling power of the semiconductor refrigeration sheet to save electricity consumption.

The control unit 8 can also control the closing and opening of the circuit.

As shown in FIG. 7 , the control unit 8 is mainly composed of a single-chip microcomputer and an H-bridge. Among them, the single-chip microcomputer communicates with the computer through the USB interface, and controls the H-bridge to work after receiving the computer command. The H bridge receives the single-chip microcomputer command, regulates the current of the TEC semiconductor refrigeration chip 2, and makes the freezer of the present invention realize the conversion of the following working states:

(1) Freezing condition

The single-chip microcomputer outputs a high level to the two interfaces of PWM1 and PWM4, and outputs a low level to PWM2 and PWM3, so that the MOS transistors Q1 and Q4 in the H bridge are turned on, the MOS transistors Q2 and Q3 are turned off, the OUT1 terminal outputs a high voltage, and the TEC The semiconductor refrigeration chip is conducting forward and enters the refrigeration working state. The duty cycle of the PWM1 and PWM4 signals is adjusted by the single-chip microcomputer, and the voltage of the output terminal is adjusted, thereby changing the refrigeration power of the semiconductor refrigeration chip.

(2) Heating condition

The single-chip microcomputer outputs a high level to the two interfaces of PWM2 and PWM3, and outputs a low level to PWM1 and PWM4, so that the MOS transistors Q2 and Q3 in the H bridge are turned on, the MOS transistors Q1 and Q4 are turned off, the OUT2 terminal outputs a high voltage, and the TEC The semiconductor refrigeration chip conducts reversely and enters the exothermic working state. The duty cycle of the PWM1 and PWM4 signals is adjusted by the single-chip microcomputer, and the voltage of the output terminal is adjusted, thereby changing the heat dissipation power of the semiconductor refrigeration chip.

(3) Closed state

When the four groups of PWM signals of the single-chip microcomputer are all low level, the MOS tube is not turned on, and it will not provide working voltage for the TEC semiconductor refrigeration chip, and the semiconductor refrigeration chip stops working.

To sum up, the freezer of the present invention utilizes the thermoelectric effect of the semiconductor material to cool, and dissipates heat through the heat sink, and uses the control unit to control the current switch, direction and size of the semiconductor refrigerating sheet, so as to achieve segmental freezing, directional freezing and Forced thawing greatly reduces engineering costs and construction period, reduces costs, saves energy, and improves work efficiency.

A thermoelectric refrigeration artificial formation freezer of the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can obtain other embodiments according to the technical solutions of the present invention, which also belong to the technical innovation scope of the present invention.

Claims (5)

1. A semiconductor refrigerating sheet of a freezing device, comprising a semiconductor refrigerating sheet (2), characterized in that the semiconductor refrigerating sheet (2) can be configured to have single-stage refrigeration, two-stage refrigeration or multi-stage refrigeration according to the The freezing device can adjust the working state of different sections in a level manner, so as to realize freezing and forced thawing in stages; ), a liquid return space is formed between the heat dissipation pipe (3) and the liquid supply pipe (6), the heat dissipation pipe (3) is provided with a liquid discharge hole (9), and the liquid discharge hole (9) is connected with the liquid return space The control unit includes a single-chip microcomputer and an H-bridge, the single-chip microcomputer communicates with the computer through the interface, receives the computer commands and controls the H-bridge to work; the H-bridge receives the single-chip microcomputer commands and regulates the current of the semiconductor refrigeration chip; the control unit (8) can independently control the protection tube (1) A semiconductor refrigeration sheet (2) in a certain area or a certain length, so as to achieve segmental freezing and directional freezing; the semiconductor refrigeration sheet (2) has a heat absorption end (5) and a heat release end (4), wherein , the heat absorbing end (5) is attached to the inner wall of the protection tube (1) of the freezing device, and the heat releasing end (4) is attached to the outer wall of the cooling tube (3) of the freezing device; 2) In the case of electrification, the heat absorption end (5) absorbs the formation heat, and the heat release end (4) takes the formation heat away through the heat dissipation pipe (3). 2. A freezing device for freezing strata in sections, comprising at least a protection pipe (1) and a heat dissipation pipe (3), characterized in that it also comprises the semiconductor refrigeration sheet (2) according to claim 1, wherein the semiconductor refrigeration sheet (2) It can be distributed in the axial and/or circumferential direction between the protection pipe (1) and the heat dissipation pipe (3); the control unit (8) can independently control the circuit and current of any group of semiconductor refrigeration chips (2). In the case of the size and direction, the control unit (8) can achieve segmental freezing in a manner of individually controlling the semiconductor refrigeration sheet (2) of a certain length in the protection tube (1). 3. The freezing device for segmented freezing of strata according to claim 2, characterized in that the space formed between the protection pipe (1), the heat dissipation pipe (3) and the semiconductor refrigeration sheet (2) is provided with a space for detection and protection A temperature sensor (14) for the temperature of the pipe (1) and the radiating pipe (3), the temperature sensor (14) is installed in the wire and the temperature sensor slot (7) and connected with the computer. 4. A method for thawing a freezing device, characterized in that it comprises at least a semiconductor refrigeration sheet (2), a control unit (8) and a heat dissipation device, and when circulating cooling water flows into the heat dissipation device, the semiconductive refrigeration The sheet (2) realizes the exchange of the heat absorbing end and the exothermic end of the semiconductor refrigeration sheet (2) according to the reverse current mode, thereby forcibly thawing the artificially frozen stratum; The heat dissipation device is a water-cooled sleeve type radiator, comprising an external heat dissipation pipe (3) and an internal liquid supply pipe (6), and a liquid return space is formed between the heat dissipation pipe (3) and the liquid supply pipe (6), and the heat dissipation pipe (3) and the liquid supply pipe (6) form a liquid return space. The pipe (3) is provided with a drain hole (9), and the drain hole (9) is communicated with the liquid return space; the control unit includes a single-chip microcomputer and an H-bridge, and the single-chip microcomputer communicates with a computer through an interface, and receives computer commands. And control the H-bridge work; the H-bridge receives the command of the single-chip microcomputer, and regulates the current of the semiconductor refrigeration chip; The control unit (8) can independently control a certain area or a certain length of the semiconductor refrigeration sheet (2) in the protection tube (1), so as to achieve segmental freezing and directional freezing; The semiconductor refrigeration sheet (2) has a heat-absorbing end (5) and a heat-releasing end (4), wherein the heat-absorbing end (5) is attached to the inner wall of the protection tube (1) of the freezing device, and the heat-emitting end (5) is The end (4) is attached to the outer wall of the heat dissipation pipe (3) of the freezing device; when the semiconductor refrigeration sheet (2) is energized, the heat absorbing end (5) absorbs the heat of the formation, and the heat releasing end (4) ) takes the heat away from the formation through the radiating pipe (3). 5. The thawing method of a freezing device according to claim 4, wherein the control unit (8) regulates the working states of the solid-state refrigeration devices of different sections of the freezing device along its axial direction respectively according to the thawing requirements, To achieve segmental thawing; Wherein, the solid-state refrigeration device is composed of a plurality of directionally arranged semiconductor refrigeration sheets.

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